Frozen ground fish particles and process for preparing

ABSTRACT

Disclosure is made of a process for producing materials for fish paste products which comprises the step 1 of milling a frozen ground fish meat to thereby give a frozen ground fish meat in the form of fine particles having a diameter of 1 mm or less, thawing a frozen ground fish meat under milling to thereby give a thawed ground fish meat in the form of fine particles, or thawing a frozen ground fish meat and then cutting it to thereby give a thawed ground fish meat, and the step 2 of mixing under stirring the ground fish meat obtained in the step 1 with the use of a stirring means, provided that a cake mixer is employed as the stirring means, when a frozen ground fish meat is thawed to give thawed ground fish meat in the step 1. Use of this process makes it possible to efficiently provide materials ensuring the production of fish paste products with good qualities, e.g. improved gel strength.

TECHNICAL FIELD

This invention relates to a process for producing materials for fishpaste products; materials for fish paste products produced by thisprocess; and frozen ground fish meats in the form of fine particleswhich are intermediates in the above-mentioned process.

BACKGROUND ART

In general, fish paste products are produced by adding sodium chlorideto ground fish meat, mixing it with stirring (so-called "shio-zuri"),adding seasonings, starch, water, etc. thereto, molding the resultingmixture and then heating it. The ground fish meats employed as thestarting materials are usually stored and transported in a frozen stateand widely utilized as materials for producing various food products.

Fishes processed into ground fish meats are exemplified by croaker(Nibea mitsukuri), swordfish (Makaira mazara), sand borer (Argentinasemifasciatus KISHINOUE), lizardfish (Saurida undosquamis), warazuka(Stichaeus grigorjewi HERZENSTEIN) and Alaska pollack (Theragrachalcogramma). In recent years, Alaska pollack, etc. have been mainlyemployed therefor because of the decrease in the trawl fishery catch.However, pollacks are liable to be denatured in meat qualities duringthe freezing step. Thus, it has been a practice to add about 5% of sugarto frozen ground fish meat for preventing the denaturation and, at thesame time, to thoroughly leach the ground fish meat with water so as toeliminate water-soluble enzyme proteins and salts, which participate inthe denaturation during freezing, therefrom.

Frozen ground fish meat is produced via the following steps. First, thefishes are washed. After removing the heads and internals, the fishesare washed again and the meat is collected therefrom. The fish meat thuscollected is next leached with 4 to 5 times as much water so thatwater-soluble proteins and salts are eliminated therefrom as far aspossible. Subsequently, the fish meat is pressed, dehydrated andstrained. After adding 5 to 10% of sugar and 0.2% of polyphosphates, theobtained blend is well mixed. 10 kg of this mixture is packed in apolyethylene film and rapidly frozen at about -35° C. with the use of acontact freezer to thereby give frozen ground fish meat. The frozenground fish meat is stored usually at -15 to -25° C.

The conventional process for producing fish paste products from thefrozen ground fish meat thus produced comprises thawing the frozenground fish meat by using, for example, a hot water thawing machine,crushing the ground fish meat thus thawed with a cutter, putting sodiumchloride thereon and then milling it (shio-zuri). However, thisconventional process leaves room for improvement, since it takes a lotof time and labor therefor. Moreover, it is necessary to furtherelaborate the production process per se to produce fish paste productswith improved qualities.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a process by whichmaterials for fish paste products ensuring the production of fish pasteproducts with good qualities can be efficiently produced. Another objectof the present invention is to provide materials for fish paste productsensuring the production of fish paste products with good qualities.Another object of the present invention is to provide frozen ground fishmeats in the form of fine particles which are useful in the productionof excellent fish paste products. Other objects of the present inventionwill be apparent from the following description and the technical levelat the filing date of the application.

These objects of the present invention have been achieved by providingthe present invention as will be described hereinbelow.

The present invention provides a process for producing materials forfish paste products which comprises the step 1 of milling a frozenground fish meat to thereby give a frozen ground fish meat in the formof fine particles, thawing a frozen ground fish meat under milling tothereby give a thawed ground fish meat in the form of fine particles, orthawing a frozen ground fish meat and then cutting it to thereby give athawed ground fish meat, and the step 2 of mixing under stirring theground fish meat obtained in the step 1 with the use of a stirringmeans, provided that a cake mixer is employed as the stirring means,when a frozen ground fish meat is thawed to give a thawed ground fishmeat in the step 1.

The present invention further provides materials for fish paste productsproduced by this process. The present invention furthermore providesfrozen ground fish meats in the form of fine particles having an averageparticle diameter of 1 mm or less which are usable as an intermediate inthe above-mentioned production process.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a graph showing the relationship between the particle diameterof the frozen ground fish meats in the form of fine particles and gelstrength (refer to Test Example 1).

BEST MODE FOR CARRYING OUT THE INVENTION

In the step 1 or the process for producing materials for fish pasteproducts according to the present invention, a frozen ground fish meatis processed into an intermediate product which can be mixed understirring in the subsequent step 2. More particularly speaking, theprocedure in the step 1 is carried out by milling a frozen ground fishmeat to thereby give a frozen ground fish meat in the form of fineparticles, thawing a frozen ground fish meat under milling to therebygive a thawed ground fish meat in the form of fine particles, or thawinga frozen ground fish meat and then cutting it to thereby give a thawedground fish meat.

The frozen ground fish meat to be used in the present invention is notparticularly restricted in type. In the present invention, namely, usecan be made of frozen ground fish meats of various types without anylimitation in fish type, composition ratio, qualities, catch area,freezing conditions, weight, shape, storage time, moisture content,seasoning contents, salt content, etc. Also, use can be made of a frozenground fish meat containing seasonings, salt, etc. Either one frozenground fish meat or an appropriate combination thereof may be employedin the present invention.

In the step 1 of the present invention, it is preferable to prepare afrozen ground fish meat in the form of fine particles of a thawed groundfish meat in the form of fine particles via a frozen ground fish meat inthe form of fine particles. In such a case, the average particlediameter of the milled meat is regulated so that all of the particlescan be uniformly thawed. More particularly, the average particlediameter is regulated preferably to 1 mm or less, still preferably to0.5 mm or less and still preferably to 0.1 mm or less. The term "averageparticle diameter" as used herein means the value calculated by dividingthe total of the products of each particle size by the number of thecorresponding particles by the sum of the particles. That is to say,neither diameter of the largest particle nor that of the smallest one islimited in particular. It is preferable that all of the milled meatparticles have diameters of 1 mm or less, still preferably 0.5 mm orless and still preferably 0.1 mm or less. The ground fish meat in theform of fine particles, the upper limit of the diameter of which hasbeen thus determined, can be prepared by putting the ground fish meatthrough a sieve with a pore size corresponding to the upper limit of theparticle diameter.

The frozen ground fish meat in the form of fine particles or the thawedground fish meat in the form of fine particles can be prepared by usinga mill by which ground fish meat in a frozen state can be milled. Forexample, use may be made therefor of a rotary mill having a rotorprovided with pins or a cutter on the surface thereof by which a frozenground fish meat can be milled or a reciprocal mill having areciprocating board provided with pins or a cutter on the surfacethereof by which a frozen ground fish meat can be milled. The millingcan be performed either in a single step or in two or more steps so thatthe desired average particle diameter can be achieved. When the millingis performed in two or more steps, it is preferable that the ground fishmeat is milled in two steps, i.e., the first step of roughly crushingand the second step of finely milling.

To prepare a frozen ground fish meat in the form of fine particles, themilling is carried out at such a temperature that the frozen ground fishmeat is maintained in the frozen state. That is to say, the temperatureof the frozen ground fish meat is maintained at 0° C. or below,preferably -12° C. or below, still preferably -15° C. or below and stillpreferably -20° C. or below. To prepare a thawed ground fish meat in theform of fine particles, a frozen ground fish meat in the form of fineparticles may be once prepared and then thawed in a conventional manner.Alternatively, the frozen ground fish meat may be thawed and milled atthe same time by setting the milling temperature at a relatively highlevel.

The frozen ground fish meat in the form of fine particles may be mixedwith an aqueous solution of sodium chloride. For example, the aqueoussolution of sodium chloride may be added to the frozen ground fish meatimmediately after milling via an inlet therefor formed in the mill.Alternatively, the aqueous solution of sodium chloride may be added tothe frozen ground fish meat outside the mill. The amount andconcentration of the aqueous solution of sodium chloride may beappropriately selected within the range needed in shio-zuri. The sodiumchloride may be replaced by strong electrolytes such as potassiumchloride.

The frozen ground fish meat in the form of fine particles, which hasbeen milled to give a definite particle size as being in the frozenstate, is remarkably useful as a material for producing fish pasteproducts. By using the frozen ground fish meat in the form of fineparticles having a particle size of 1 mm or less, in particular, itbecomes possible to produce fish paste products having highly excellentgel properties. This fact has been confirmed by examining the particlediameter of frozen ground fish meats in the form of fine particles andthe gel strength of fish paste products obtained by mixing the frozenground fish meat with an aqueous solution of sodium chloride and thenstirring, molding and heating the mixture (refer to Test Example 1).FIG. 1 shows the relationship between these factors. As FIG. 1 shows,the gel strength is slowly elevated with a decrease in the particlediameter but surprisingly shows a rapid increase at the particlediameter of 1 mm or less. That is to say, fish paste products havinghigh gel strength and excellent qualities can be efficiently produced byusing frozen ground fish meats in the form of fine particles havingparticle diameter of 1 mm or less (refer to Test Example 2). It is alsopossible to delicately regulate the gel strength of fish paste productsby appropriately controlling the particle diameter within the scope ofthe present invention. Namely, the gel strength of products can bealtered by merely changing the particle diameter of the frozen groundfish meat in the form of fine particles employed as the feedstock evenin a single plant operated under the same conditions, which brings aboutan extremely large industrial advantage.

When the frozen ground fish meat in the form of fine particles isemployed, furthermore, the ground fish meat can be mixed in the frozenstate with an aqueous solution of sodium chloride and then quicklytreated in the subsequent step as such, which contributes to theprevention of the deterioration of the ground fish meat. When the frozenground fish meat is thawed by the conventional process, it isunavoidable that the surface of the frozen ground fish meat alone is atfirst thawed and deteriorated. Moreover, the frozen ground fish meatthawed by the conventional method cannot be milled into fine particlesof 1 mm or less in particle diameter, which makes it impossible to givefish paste products with high gel strength. In contrast, use of thefrozen ground fish meat in the form of fine particles makes it possibleto solve these problems encountering in the prior art and thus providefish paste products with excellent qualities. In addition, the frozenground fish meat in the form of fine particles can be easily weighed andthus makes it possible to produce a small amount of fish paste productsor delicately control the amount of the ground fish meat employed whichcan be hardly made in the conventional method of weighing frozen groundfish meat plates.

In addition to the particularly preferable procedures as describedabove, the step 1 in the process for producing materials for fish pasteproducts of the present invention involves a procedure which comprisesthawing and cutting a frozen ground fish meat to thereby give a thawedground fish meat. When this procedure is employed, however, a cake mixershould be used in the subsequent step 2. The frozen ground fish meat canbe thawed in a conventional manner, for example, on a plate throughwhich hot water about 30 to 60° C. is circulated.

The ground fish meat prepared in the step 1 is optionally mixed with anaqueous solution of sodium chloride. The amount and concentration of theaqueous solution of sodium chloride may be appropriately selected withinthe range needed in shio-zuri. When the frozen ground fish meat alreadycontains a sufficient amount of sodium chloride, then this mixing stepwith the aqueous solution of sodium chloride is omitted. As describedabove, the sodium chloride may be replaced by strong electrolytes suchas potassium chloride.

In this step, seasonings and food ingredients other than the ground fishmeat may be added thereto. For example, addition may be optionally madeof starch, mirin (sweetened sake seasoning), synthetic seasonings suchas sodium glutamate, egg albumen, sugar, flavors, etc.

The mixture thus obtained my be optionally degassed. This degassingprocedure may be performed depending on the type of the desired finalproduct. To produce kamaboko, etc., it is preferable to perform thisdegassing. In general, the degassing is carried out after adding theaqueous solution of sodium chloride and then the degassed product ismixed with seasonings, though the order of these procedures may beappropriately altered.

After optionally degassing and/or mixing with seasonings, the obtainedmixture is subjected to the mixing under stirring in the step 2. Theterm "mixing under stirring" as used herein involves not only literallystirring but also cutting and kneading. The mixing under stirring can becarried out by using a stirrer usable in the production of fish pasteproducts. For example, use may be made therefor of a stone mortar typemill, a food cutter, a silent cutter, a homogenizer, a Stefan cutter(manufactured by Stefan K.K.), a kneader, a ball cutter (manufactured byYanagiya K.K.), a capsule cutter (manufactured by Bibun K.K.), a pinmixer, a kneading machine, etc under appropriate conditions.

When the mixing under stirring is carried out by using a pin mixer,final products with high gel strength can be efficiently produced. Itis, therefore, preferable in the present invention to use a pin mixer inwhich the feedstock is mixed with a rotor provided with pins insertedinto a stator. The feedstock is supplied from one end of the statorwhile the mixture is discharged from another end thereof. The pins maybe arranged arbitrarily without restriction. For example, use can bemade of a pin mixer having a rotor with pins located thereon in spiral.By using such a pin mixer, the mixture can be continuously stirred. As aresult, the efficiency in the production process of fish paste productscan be largely elevated and the products can be obtained within arelatively short time while preventing the deterioration due toprolonged retention. It has been confirmed in practice that the treatingtime can be halved by using a pin mixer, compared with the cases whereinbatch type meachines are employed. In addition, the contact of themixture with the atmosphere during the production process is lessened,which enables hygienically preferable production. Furthermore, theelevated economical efficiency in the production brings about greatadvantages in practice. Shio-zuri with the use of a pin mixer isdescribed in JP, 3-41145, B as cited herein as a reference.

In the step 2 of the process of the present invention, use may be madeof a cake mixer. When a frozen ground fish meat is thawed and cut tothereby give a thawed ground fish meat in the step 1, in particular, thestirrer to be used in the step 2 is restricted to a cake mixer. The cakemixer is not restricted in type. A cake mixer consists of a stirrer anda round-bottomed bowl. The stirrer may have any sectional shape, forexample, a triangular, rectangular, diamond-shaped, square, trapezoid,pentagonal, hexagonal, round or oval one. Since there is some spacebetween the bottom of the bowl and the stirrer, no friction arisesbetween the stirrer and the wall during stirring. Namely, it isadvantageous to use a cake mixer so as to prevent the increase in thetemperature of the ground fish meat. The stirring unit is covered andthus one can safely operate the mixer without touching the unit. Thebowl can be conveyed separately from the stirrer. Accordingly, the bowlis usable not only in stirring/kneading but also in, for example,weighing, transporting or storing the mixture containing the ground fishmeat. By using the cake mixer, a series of these operations can becompleted without transferring the mixture into another container, whichfacilitates the operations. The cake mixer has an additional advantagethat it is relatively cheap and can be easily washed because of itssimple structure. By taking the stirring efficiency into consideration,it is preferable that the stirring with the cake mixer is performedunder such conditions as to give the particle diameter or averageparticle diameter of the material of 1 mm or less.

The materials for fish paste products thus produced may be furthermolded and processed, by methods appropriately selected by those skilledin the art, into fish paste products such as kamaboko, chikuwa andhanpen. In usual, the processing steps involve heating, cooling, etc.The cooling may be carried out by an appropriately selected method suchas allowing to cool or quenching. The fish paste products thus producedhave high gel strength, good elasticity and excellent qualities.

To further illustrate the present invention in greater detail, and notby way of limitation, the following Examples will be given.

EXAMPLE 1

10 kg of frozen ground Alaska pollack meat (SA grade) was milled at -18°C. by using a marketed rotary mill having a rotor provided with amachined cutter on its surface. When the particle diameter distributionof the frozen ground fish meat in the form of fine particles thusobtained was microscopically observed, most of the particles showedparticle diameters falling within the range of 1 to 0.5 mm and theaverage particle diameter was less than 1 mm.

Further, this frozen ground fish meat in the form of fine particles wasput through 1 mm-, 0.5 mm- and 0.1 mm-sieves to thereby give frozenground fish meats in the form of fine particles of 1 mm or less, 0.5 mmor less and 0.1 mm or less in particle diameter.

Furthermore, these frozen ground fish meats in the form of fineparticles were allowed to stand at room temperature to thereby givethawed ground fish meats in the form of fine particles.

EXAMPLE 2

10 kg of frozen ground Alaska pollack meat (SA grade) was milled at -18°C. by using a marketed rotary mill having a rotor provided with amachined cutter on its surface. When the particle diameter distributionof the frozen ground fish meat in the form of fine particles thusobtained was microscopically observed, most of the particles showedparticle diameters falling within the range of 0.5 to 0.1 mm and theaverage particle diameter was less than 0.5 mm.

Further, this frozen ground fish meat in the form of fine particles wasput through 0.5 mm- and 0.1 mm-sieves to thereby give frozen ground fishmeats in the form of fine particles of 0.5 mm or less and 0.1 mm or lessin particle diameter.

Furthermore, these frozen ground fish meats in the form of fineparticles were allowed to stand at room temperature to thereby givethawed ground fish meats in the form of fine particles.

EXAMPLE 3

10 kg of frozen ground Alaska pollack meat (SA grade) was milled at -18°C. by using a marketed rotary mill having a rotor provided with amachined cutter on its surface. When the particle diameter distributionof the frozen ground fish meat in the form of fine particles thusobtained was microscopically observed, the average particle diameter wasless than 0.1 mm.

Further, this frozen ground fish meat in the form of fine particles wasput through a 0.1 mm-sieve to thereby give a frozen ground fish meat inthe form of fine particles of 0.1 mm or less in particle diameter.

Furthermore, these frozen ground fish meats in the form of fineparticles were allowed to stand at room temperature to thereby givethawed ground fish meats in the form of fine particles.

EXAMPLE 4

To 10 kg of each of the frozen ground fish meats in the form of fineparticles produced in the above Examples 1 to 3 was added 3 liters of a14.2% aqueous solution of sodium chloride. The frozen ground fish meatmixture containing the aqueous solution of sodium chloride thus obtainedwas stirred in a cake mixer (manufactured by Kanto Kongoki Kogyo K.K.)for 35 minutes to thereby give a material for fish paste products.

The above procedure was repeated but using a silent cutter (manufacturedby Bibun K.K.) as a substitute for the cake mixer to thereby give amaterial for fish paste products.

Further, the above procedure was repeated but using a pin mixer(manufactured by Kibun Shokuhin K.K.: refer to JP, 3-41145, B) as asubstitute for the cake mixer to thereby give a material for fish pasteproducts.

Furthermore, the above procedure was repeated but kneading the mixturewith a kneader (manufactured by Kajihara Kogyo K.K.) for 5 minutes andoptionally degassing prior to the stirring with the pin mixer to therebygive a material for fish paste products.

By using these materials, kamaboko, chikuwa and hanpen were produced.The fish paste products thus obtained were all excellent ones havinghigh gel strength and good elasticity.

EXAMPLE 5

10 kg of frozen ground Alaska pollack meat (SA grade) was thawed byusing a press thawing machine with hot water at 30° C. When measured inthe thawing step, the center temperature of the ground fish meat was -5°C. Then 5 liters of a 14.2% aqueous solution of sodium chloride wasadded to this thawed ground fish meat and the obtained mixture wasstirred in a cake mixer for 35 minutes to thereby give a material forfish paste products.

The above procedure was repeated but kneading the mixture with a kneader(manufactured by Kajihara Kogyo K.K.) for 5 minutes prior to thestirring with the cake mixer to thereby give a material for fish pasteproducts.

Test Example 1

In this Test Example, fish paste products were produced by using frozenground fish meats in the form of fine particles having various particlediameters and thus the relationship between the particle diameter andthe gel properties of the obtained fish paste products was examined.

10 kg of frozen ground Alaska pollack meat (SA grade) was milled at -18°C. by using a marketed rotary mill having a rotor provided with amachined cutter on its surface. Next, this frozen ground fish meat inthe form of fine particles was put through 5 mm- and 3 mm-sieves tothereby give a frozen ground fish meat in the form of fine particleshaving a particle diameter of 5 mm or less (sample 1) and another frozenground fish meat in the form of fine particles having a particlediameter of 3 mm or less (sample 2). Then the test was performed byusing these samples 1 and 2 together with the frozen ground fish meat inthe form of fine particles having a particle diameter of 1 mm or lessproduced in Example 1 (sample 3), the one having a particle diameter of0.5 mm or less produced in Example 2 (sample 4) and the one having aparticle diameter of 0.1 mm or less produced in Example 3 (sample 5).

Each sample was stirred with a silent cutter in the same manner as theone described in Example 4 and then molded in a casing tube. Aftergelation at 35 °C for 60 minutes, it was heated to 85° C. for 30 minutesand then refrigerated overnight. Next, the gel strength was measuredwith a rheolometer (manufactured by Ai-Techno K.K.; 1 mm in width, wedgeplunger). The results of the test are summarized in the following Table1, while FIG. 1 shows a graph of the data. Each gel strength isexpressed in a relative value calculated by referring that sample 5 asto 100%.

                  TABLE 1    ______________________________________    Sample No.  Particle size (mm)                            Gel strength (%)    ______________________________________    1           5 or less   57    2           3 or less   60    3 (invention)                1 or less   70    4 (invention)                0.5 or less 85    5 (invention)                0.1 or less 100    ______________________________________

Test Example 2

In this Test Example, comparison was made between a material for fishpaste products produced by stirring a frozen ground fish meat (frozensurimi) in the form of fine particles with a silent cutter and anotherone produced by stirring a thawed ground fish meat with a silent cutter.

10 kg of frozen ground Alaska pollack meat (SA grade) was thawed byusing a press thawing machine with hot water at 30° C. When measured inthe thawing step, the center temperature of the ground fish meat was -5°C. This thawed ground fish meat was milled with a silent cutter for 15minutes and then mixed with 3 liters of a 14.2% aqueous solution ofsodium chloride to thereby give a material for fish paste products(sample 6). This sample and the material for fish paste productsobtained in Example 4 (sample 7), which had been produced by stirring afrozen ground fish meat in the form of fine particles with a silentcutter, were subjected to a comparison test in the same manner as theone of Test Example 1. Thus, it was confirmed that the sample 6 had alow gel strength of 75%, determined by referring the gel strength of thesample 7 as to 100%.

On the other hand, the sample of Example 5, which had been produced bystirring a thawed ground fish meat with a cake mixer to thereby give amaterial for fish paste products, had a significantly higher gelstrength than that of the sample 6.

Industrial Applicability

Use of the process for producing materials for fish paste products ofthe present invention makes it possible to efficiently provide materialsensuring the production of fish paste products with good qualities.Frozen ground fish meats in the form of fine particles having averageparticle diameter of 1 mm or less, i.e., the intermediate products inthe process of the present invention, are highly useful as materials forproducing fish paste products with high gel strength and excellentqualities. Accordingly, the present invention is widely usable in theindustrial fields with the use of frozen ground fish meats andapplicable over an extremely broad range.

We claim:
 1. A frozen ground fish meat in the form of fine particleshaving an average particle diameter of 1 mm or less.
 2. The frozenground fish meat in the form of fine particles as claimed in claim 1having an average particle diameter of 0.5 mm or less.
 3. The frozenground fish meat in the form of fine particles as claimed in claim 1having an average particle diameter of 0.1 mm or less.
 4. A frozenground fish meat in the form of fine particles as claimed in claim 1containing sodium chloride.
 5. A frozen ground fish meat in the form offine particles as claimed in claim 1 produced by crushing a frozenground fish meat followed by milling.